This is not the start of summer. I repeat, this is not the start of summer.

Something happened whilst I was having a wonderful time on holiday, and I’ve not really researched it much…well…at all. Namely that there was a strong final warming of the stratosphere, pretty much akin to a sudden stratospheric warming (SSW) event…I think.

An SSW in winter greatly increases the chance of significant cold spells in the coming 2-6 weeks, through high pressure blocks across our latitude, and cold air then pours out of the Arctic on the eastern side of said blocks.

Of course, it isn’t winter – it is 24 days into spring and the continent is warming. So an easterly may not be cold now – though a northerly would.

And there might be a northerly next week. And maybe, just maybe, some wintry showers. Well…it is spring.

Thanks to Liz for the photograph.

Tonight sees clear spells and it will be chilly, down to around 3’C – a frost in the most sheltered spots possible.

Friday sees high pressure remain in control, though we start to pick up a slight easterly breeze – losing the warm southerly.

Long spells of sunshine, a bit of high cloud at times and some fair weather cloud in the afternoon. Still on the warm side, 18’C should be reached, maybe a tad more. Clear skies overnight, broadly down to around 3’C though a frost possible in the most sheltered spots.

Saturday will be another very pleasant day with long spells of sunshine, and just a bit of fair weather cloud. Reaching around 18’C, maybe 19’C. Clear skies at first overnight but low cloud spilling across from the North Sea later in the night, down to around 5’C.

Sunday starts cloudy. It should clear to sunshine at some point – the morning is probably too optimistic, at some point in the afternoon will be more likely. Temperatures dependant on how long it takes the cloud to clear, so somewhere between 12’C and 17’C. Clear skies probable overnight for a while, mist/fog forming in places towards dawn and low cloud in others. Down to around 3’C, very give and take – no mist/fog and you may get a frost. All going to be pretty localised and difficult to give exact details right now.

Monday starts with mist/cloud/low cloud for most, not all. This will clear to sunny spells, and some cloud – a very small chance of an afternoon shower. Quite warm once more, 16’C or so. Uncertain on overnight conditions.

Tuesday sees colder weather spread down from the north – though at the same time low pressure edges up from Spain.

Details are sketchy as the low pressure to our south will probably make the colder air’s journey not so clean cut. Roughly speaking, cloudy, around 12’C with the odd shower – but the margins are fine so something notably colder, something sunny, something wet or even the quite warm air hanging on a bit longer are all possible.

It’s really too difficult to call from here. There are two broad patterns that I think are more likely.

The slightly more likely outcome for Wednesday to Friday sees the cold air properly sweep south, with daytime temperatures of somewhere between 4’C and 6’C, sleet and snow showers (yeah) and overnight frosts.

The slightly less likely outcome would see the cold air not quite make it down, but there would be rain/showers and temperatures around 10’C to 13’C – that kind of range.

Next weekend is very uncertain! The colder solution would be drier, the less cold solution would be more unsettled, though perhaps quite warm.

Generally the start of April is more likely to be unsettled than not.

And then it will be a case of seeing what impact (further impact?) the strong final warming of the stratosphere has. I was already expecting northerly flows to be more likely towards the end of April, in my spring forecast – maybe this is more likely now but I’m very uncertain. I need to do some research!